Electrical circuits (e.g. controllers) that control the coupling or application of a high-side voltage and a low-side voltage to an electrical load such as an electric motor or a fuel injector are known. Such controllers commonly have a high-side circuit that controls the application of the high-side voltage to a terminal of the load, and a low-side circuit that controls the application of the low-side voltage to a terminal of the load. The low-side circuit may include signal-processing logic and/or a processor with low-voltage signals that are typically referenced to a ground-reference (e.g. ground voltage). However, the high-side circuit may be referenced to a voltage other than ground, an offset voltage such as a high-side terminal of the load for example. Such a configuration typically requires the controller to include a level-shift circuit so the ground referenced logic signals can be coupled or transitioned to the high-side circuit.
It has been observed that level-shift circuits that transmit data between the high-side circuit and the low-side circuit can be corrupted by noise present between the different voltage references of the respective circuits. The noise may be caused by, for example, capacitive displacement current in the level shifters. Such noise can cause the voltage difference between the different voltage references to vary or fluctuate, so can result in data transmission errors (e.g. false 1s and 0s) between the two circuits. Prior attempts at filter incoming data or messages incur an undesirable delay when high speed messaging is essential. However, validation of data at the destination is desired to assure that the correct digital message has been received. Another alternative is to reply with received data by feeding the received message from the destination back to the source, i.e. back to the circuit that originated the received message. However, this feedback signal is susceptible to the same noise that corrupts the message from the source, and also incurs undesirable delays.